In-medium effects on the $K^{-}/K^{+}$ ratio at GSI

Abstract

The in-medium modifications on the $K^{-}/K^{+}$ ratio produced at GSI are studied. Particular attention is paid to the properties of antikaons, which determine the chemical potential and temperature at freeze-out conditions. Different approaches have been considered: non-interacting $K^{-}$, on-shell self-energy and single-particle spectral density. We observe that the full off-shell approach reproduces the "broad-band equilibration" advocated by Brown being the spectral density crucial to explain an enhanced $K^{-}/K^{+}$ ratio.

Comments: 4 pages, 3 figures. Contributed parallel talk to the International Conference on Hypernuclear and Strange Particle Physics (HYP2003), Jefferson Lab, Newport News, Virginia (USA), Oct 14-18, 2003